Ototoxicity effects of low exposure to solvent mixture among paint manufacturing workers

Abstract

Objective: To evaluate auditory function in a group of workers exposed to organic solvent mixture at a paint factory. Design: Cross-sectional study. Study sample: One hundred and sixty-one workers were studied, 77 exposed to solvents and 84 unexposed. Fourteen solvents were measured, including toluene, xylene, and n-hexane. Pure-tone audiometry and brainstem auditory-evoked potentials (BAEP) were performed. Industrial noise was < 85 dBA and exposure levels to organic solvents were low. Results: The exposed group showed a hearing impairment in both ears compared with the unexposed workers. Multiple linear regression models adjusted by age, chronic pathologies, and environmental noise for frequency means between 125 and 8000 Hz produced the following results: for the left ear, R² = 33.3%, exposed vs. unexposed β = 4.1 (p < 0.001); and for the right ear, R² = 38%, exposed vs. unexposed β = 4.8 (p < 0.001). Adjusted for age and chronic pathologies, waves III and V, and interpeak interval latencies were increased (p < 0.05) in both ears in the exposed group. Conclusions: Although solvent mixture concentrations and noise levels were low, our results demonstrate that there may be a concurrent ototoxicity and neurotoxicity condition and emphasize the importance of including BAEP analysis for comprehensive assessments. Future studies that include otoacoustic emissions assessments to monitor cochlear function and central auditory processing tests are imperative.

Key Words::

• Ototoxicity
• organic solvent mixture
• noise
• workers

Acknowledgements

We are grateful for the valuable collaboration of José Rito Mendieta-Zaragoza, Rosa María Barquet-Barquet, Nadia Mayola Vélez-Zamora, Rubén Rojo-Ramírez, Diana Lizeth Valero-Rodríguez, Vanessa Crystal Sanchez Escalante, and Wendoly Hinojos Escobar. We would also like to thank the organizers and scientific committee of the VIII Congreso de Medicina y Enfermería del Trabajo (Congress on Occupational Medicine and Nursing), celebrated in Valladolid, Spain, who awarded this paper as the best scientific research. Comisión Nacional de Investición and Comite de Etica, Instituto Mexicano del Seguro Social (IMSS), No. 2003-716-0021, approved the protocol. Grant support: (1) Fundación Miguel Alemán A.C. Secretaría de Salud (México). (2) Fondo para el Fomento de la Investigación. Instituto Mexicano del Seguro Social (FOFOI-IMSS): FP-2003/109; (3) Cuauhtémoc Arturo Juárez-Pérez is an Irving Selikoff International Scholar of the Mount Sinai School of Medicine; under grant 1 D43 TW00640 from the Fogarty International Center of the National Institutes of Health; (4) CONACYT (Consejo Nacional de Ciencia y Tecnología) N° SALUD-C01-060.

Declaration of interest: The authors declare no conflict of interest.